OpenType features in this family

• caltContextual alternates9 substitutions · contextuala -> b => c != d === e <= f >= ga -> b => c != d === e <= f >= gUse in sampler
• casecase36 substitutions()+-<=>@[]{|}~¡«¬±·»¿×÷‐‑–—―•‹()+-<=>@[]{|}~¡«¬±·»¿×÷‐‑–—―•‹Use in sampler
• ccmpGlyph composition2 substitutions · contextualijijUse in sampler
• ss01Slashed zero1 substitution00Use in sampler
• ss02Alternate a1 substitutiona banana at a bakera banana at a bakerUse in sampler
• zerozero1 substitution0 10 2026 0070 10 2026 007Use in sampler

Left: feature off. Right: on. Substitutions read from the font's GSUB table.

Known limitations

• Unhinted: relies on the rasteriser's own anti-aliasing. Windows GDI aliased rendering below about 12 px will look uneven.
• No variable font and no Vietnamese, Greek or Cyrillic: Basic Latin, Latin-1, Latin Extended-A, Romanian comma-below letters, a code-oriented symbol set, arrows, box drawing and block elements only.
• Ligature outlines reach back over the preceding cells (negative left bearing on the last glyph). Some terminals and editors that clip glyphs to their cell, or that draw each cell separately, will show them cut off; turn calt off there.
• Box drawing is generated geometry (exact junctions, light/heavy/double, dashes, arcs, diagonals, blocks, shades): it joins vertically only when the line height is 1.2 (the hhea metrics 960 / -240 define the cell); other line heights leave gaps.
• Secondary glyphs are first drafts: section, pilcrow, eszett, eth, at-sign inner a, the Latin Extended-A ligature forms (ij, ŀ, ʼn), the vulgar fractions and the copyright / registered marks. Core code glyphs got the review rounds.
• m, w, M, W, N, B are drawn with a lighter pen for even colour, so their stems are visibly thinner than n or H when compared at large sizes.
• The facet signature is quiet at 11 to 14 px (it shows from about 24 px up); at text sizes the family is recognised by the tile dots, the dotted zero and the flag/foot forms of i l j.
• fontbakery WARNs left: hhea.numberOfHMetrics (22, not the recommended 3: the 20 zero-width combining marks need their own hmtx entries), contour_count, soft_hyphen (U+00AD is kept and drawn as the hyphen).
• Name 'Dioptra Mono' follows 'Dioptra' (checked only by web search, no clearance).

The designer's own list, copied unchanged from the font's hand-off manifest.

Coverage by Unicode block

• Basic Latin94 / 94
• Latin-1 Supplement94 / 95
• Latin Extended-A128 / 128
• Latin Extended-B6 / 208
• Spacing Modifier Letters8 / 80
• Combining Diacritical Marks19 / 112
• Latin Extended Additional1 / 256
• General Punctuation24 / 98
• Currency Symbols2 / 33
• Letterlike Symbols1 / 80
• Arrows13 / 112
• Mathematical Operators9 / 256
• Box Drawing128 / 128
• Block Elements32 / 32
• Geometric Shapes6 / 96